4 - Aquatic locomotion Flashcards
Peer
In water there is… gravity and … buoyancy than in air
less
more (leading to increase ability to float)
Freshwater buoyancy
1000kg/m3
Seawater bouyancy
1026kg/m3
Air buoyancy
1.18kg/m3
What is important for reducing friction & turbulence?
The body shape
Forward mvmnt causes?
Frictional drag
Why do invertebrates have higher densities than fresh or marine water?
Due to their constituents - proteins and carbohydrates
- makes them less buoyant
Mechanisms uses to counteract low or maintain neutral buoyancy
- fats (lower density than proteins)
- Ionic solutions (i.e. salts)
- air
Why is the marine copepod Notostomus neutrally buoyant?
Its enlarged carapace contains a low-density body fluid
Why is the deep sea squid Helicocranchia neutrally buoyant?
(is a sluggish swimmer)
has a very large body cavity with fluid that reduces the overall density
What is best for achieving neutral buoyancy?
Air (only 5-7% air volume is needed for an organism to be buoyant in sea- or fresh-water)
Why are air-filled chambers problematic for deep diving?
the hydrostatic pressure associated with increased depth can collapse these chambers
Body types for bouynacy
- Air-filled chambers (Cephalopods)
- Rigid-walled gas chamber (cuttlebone)
How do rigid-walled gas chambers work?
Maintains gas pressure below the externa hydrostatic pressure
Cuttlefish Sepia officinalis attaining neutral buoyancy
- Uses its cuttlebone
- Cuttlebone divided into chambers rigidly supported by lamellae and pillars
The volume of gas in the cuttlebone depends on the ?
- hydrostatic pressure (HP) which forces fluids into the cuttlebone and
- osmotic pressure (OP) that withdraws fluid from the cuttlebone due to differences in solutes between the cuttlebone and blood vessels.
The underlying epithelium regulates… (Cuttlefish)
the osmotic composition of the fluid that partially fills the chambers
Thrust force
‘Force generated by a rotating propeller that enables a vessel to move through the water’
Mechanisms that generate thrust force
- Rowing
- Oscillation
- Undulation
- Jet propulsion
Rowing def
(Diving beetles)
The hydrodynamic drag (fluid resistance) from the rowing movements of the rear legs produce forward thrust during the forward phase of swimming
Oscillation def
A back and forth movement. Creates a ‘flapping’ movement and can be used to generate lift
Undulation def
involves sinusoidal waves passing down the body/a fin/fins. Creates a ‘frilly’ movement that propels the animal forward through the water column.
Sinusoidal waves def
Jet propulsion def
Thrust can be generated by expelling water from different organs or cavities
Jet propulsion creates the movement of the animal in one direction and is achieved by the expulsion of water in the opposite direction, typically from a specialised cavity
